1. Field of the Invention
The present invention relates to a method of making a fluid filter, and to a fluid filter which is a product of the described process. More particularly, the present invention relates to a method of attaching a filter housing to a porous filter element adjacent a seam of the housing, without requiring extraneous adhesives, and wherein a molten part of the filter housing adheres to, and forms a seal around the filter element.
2. Description of the Background Art
Fluid filters are commonly used for many applications. Several different types of fluid filter assemblies are known and are commercially available. Vehicles and internal combustion engines use fuel filters, air filters, and oil filters of many different types. Most of the known fluid filters include a filter element made of a porous material. The filter element may include a cylindrical or modified cylindrical tube made of porous material, as a filter medium.
The predominant practice in assembling fluid filters uses an adhesive to affix the filter element to, and to form a fluid-impervious seal around, a wall of the filter housing. The two sections of the housing are then joined together, in an aligned configuration.
In joining plastic parts together, it has generally been preferred to minimize or avoid any migration of molten plastic, sometimes called ‘flash’, inwardly in the filter housing. One example of a known plastic-welding method, seeking to block flash flow from the edge of the weld joint, is disclosed in U.S. Pat. No. 4,601,927 to Durfee.
Various filter designs have been proposed incorporating a seal formed between a housing and a filter element. Some examples of patents illustrating different types of side or edge seals are described in U.S. Pat. Nos. 4,349,363, 4,414,172, 4,634,527, 5,723,047, and 6,066,254. Further, some limited efforts have been made to use molten plastic material, from the formation of a weld joint between two housing sections, to form a seal around the filter material, such as the method disclosed in U.S. Pat. No. 5,049,274.
While the known filter designs are useful for their specified functions, a need still exists in the filtration art for an improved method of assembling a fluid filter, which securely affixes a tubular filter element to a filter housing, and which may be performed without requiring a specialized adhesive.